Remember layout on exit

[sunnyolives]

What if - on exit - CuteMarkEd remembered:

• the size of the preview window
• whether the preview is turned off

Currently I do no need the html preview as I mainly use the application for pure writing, so every time I start CuteMarked I have to drag the preview window to the side to hide it. I propose that either CuteMarked could remember this on exit, or there could be a setting to actually turn the preview off.

An related issue is that CuteMarkEd does not remember any resizing of the preview window on exit, it seems to always revert back to sharing the remaining width 50% with the input window. Yet CuteMarkEd remembers the size of the file explorer.

The issue seems related to pull 163 - Save the default layout. "Vertical | Horizontal"

I'm on Windows 7, running 0.11.1, if that would impact the experience.